Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control means. It uses the resistor ladder that is structured with various fixed resistors to implement the shunt control means. The cut-off frequency of a filter is associated with the time constant, which is determined by equivalent resistance and equivalent capacitance value in the filter circuit; therefore, the filter of the present invention allowed users to fine tune the cut-off frequency linearly through the shunt control means when the variation of the environment or process parameters of manufacture cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. The present invention also provides a means for programming the cut-off frequency to a desirous frequency value dependent upon the conditions of application within a big range. Thus, it can be used in many purposes widely with the same filter circuit.

Abstract: A Miller-compensated amplifier, having an amplifier input and an amplifier output, comprises a first gain stage, a second gain stage, a third gain stage, and a capacitor. The first gain stage has the amplifier input as a first gain stage input thereto and a first gain stage output. The second gain stage has a second gain stage input, coupled to the first gain stage output, and a second gain stage output. The third gain stage has a third gain stage input, coupled to the second gain stage output, and provides an output voltage at the amplifier output. The capacitor is coupled between the amplifier output and the second gain stage input. The second gain stage amplifies a small signal part of a current received thereby and leaves a DC component thereof substantially the same.

Abstract: A receiving method for dual-mode receiver. When a received communication signal is a wideband signal, the dual-mode receiver is configured as a direct-conversion receiver, and when a received communication signal is a narrowband signal, the dual-mode receiver is configured as a low-IF receiver.

Abstract: A voltage regulator circuit for providing a substantially constant output voltage is disclosed. The voltage regulator circuit has a voltage regulator, a current sensing and comparing circuit, a capacitive load circuit, and a control circuit. The voltage regulator generates an output current in response to a control signal to provide the output voltage. The current sensing and comparing circuit senses the output current and outputs a result signal according to a sensed output current and a predetermined current value. The control circuit generates the control signal according to the comparison result to limit the output current. The capacitive load circuit provides the control circuit with a first capacitance when the voltage regulator circuit changes from a first mode to a second mode and provides the control circuit with a second capacitance when the voltage regulator circuit changes from the second mode to the first mode.

Abstract: A power supply. The power supply provides power to a real-time clock generator when system power is not available and comprises first and second regulators, an energy storage device, and a switch. The first regulator receives a system power and generates a first regulated voltage when the system power is available. The energy storage device is coupled to a node. The second regulator comprises an input coupled to the node and provides a second regulated voltage to a real-time clock generator. The switch is coupled between the first regulator and the node. The switch is turned on when the system power is available and turned off when the system power is not available.

Abstract: A tuning loop which can tune the cut-off frequency of an active RC filter is disclosed. The cut-off frequency is determined by equivalent resistance and equivalent capacitance in an active RC filter, therefore, the tuning loop changes the equivalent resistance to tune the cut-off frequency. The time constant of the circuit is compared to see if it is equal to the applied preset time cycle after the equivalent resistance value is changed. The cut-off frequency of the filter is tuned to a preset value when the time constant in the circuit is equal to the applied preset time cycle, or the equivalent should be changed until the time constant equal to the applied preset time cycle. A precise result can be obtained after being tuned by tuning loop due to the each component of the tuning loop are operated in an environment which is equivalent to the active RC filter.

Abstract: A current mirror with a transconductance amplifier containing the current mirror with a low static current. The current mirror includes: a load with first end and a second end, the first end coupling to a first input current and a fixed voltage difference existing between the first and second ends; a first transistor, whose drain is coupled to the second end of the load, whose gate is coupled to the first end of the load, and whose source is coupled to a second input current; and a second transistor, whose drain is coupled to a third port and an output current, whose gate is coupled to the second end of the load, and whose source is coupled to the ground. The transconductance amplifier contains: a voltage amplifier stage, a transconductance stage, and a current amplifier stage for amplifying the current and containing the current mirror.

Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control devices. It uses the linear property of the MOSFET to implement the shunt control devices. Based on the first-ordered linear analysis of the transfer function of the active-RC filter, it is found that the cut-off frequency of the active-RC filter can be tuned via the effective small-signal current controlled by the shunt control devices. Therefore, the filter of the present invention allowed users for fine tune the cut-off frequency linearly through the shunt control devices when the variation of the environment or procedure parameters of manufacture (i.e. thermo-effects) cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. In addition, it needs the different cut-off frequency from the different application.

Abstract: A Miller-compensated amplifier, having an amplifier input and an amplifier output, comprises a first gain stage, a second gain stage, a third gain stage, and a capacitor. The first gain stage has the amplifier input as a first gain stage input thereto and a first gain stage output. The second gain stage has a second gain stage input, coupled to the first gain stage output, and a second gain stage output. The third gain stage has a third gain stage input, coupled to the second gain stage output, and provides an output voltage at the amplifier output. The capacitor is coupled between the amplifier output and the second gain stage input. The second gain stage amplifies a small signal part of a current received thereby and leaves a DC component thereof substantially the same.

Abstract: A bias generator that automatically adjusts its slew rate is disclosed to generate an output bias current and adjust the output bias current according to the frequency of a clock signal. The slew rate of the amplifier is thus controlled to save power. It includes: a current mirror for receiving a feedback voltage and generating an output bias current; a storage capacitor with a first end and a second end and the latter being coupled to the ground; a charging switch coupled between the output of the current mirror and the first end of the storage capacitor; a discharging switch coupled between the first end of the storage capacitor and the ground; a comparator whose input is coupled to the first end of the storage capacitor and a reference voltage; and a feedback unit coupled to the output of the comparator for outputting a feedback voltage to the current mirror.

Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control means. It uses the resistor ladder that is structured with various fixed resistors to implement the shunt control means. The cut-off frequency of a filter is associated with the time constant, which is determined by equivalent resistance and equivalent capacitance value in the filter circuit; therefore, the filter of the present invention allowed users to fine tune the cut-off frequency linearly through the shunt control means when the variation of the environment or process parameters of manufacture cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. The present invention also provides a means for programming the cut-off frequency to a desirous frequency value dependent upon the conditions of application within a big range. Thus, it can be used in many purposes widely with the same filter circuit.

Abstract: A bias generator that automatically adjusts its slew rate is disclosed to generate an output bias current and adjust the output bias current according to the frequency of a clock signal. The slew rate of the amplifier is thus controlled to save power. It includes: a current mirror for receiving a feedback voltage and generating an output bias current; a storage capacitor with a first end and a second end and the latter being coupled to the ground; a charging switch coupled between the output of the current mirror and the first end of the storage capacitor; a discharging switch coupled between the first end of the storage capacitor and the ground; a comparator whose input is coupled to the first end of the storage capacitor and a reference voltage; and a feedback unit coupled to the output of the comparator for outputting a feedback voltage to the current mirror.

Abstract: A current mirror with a transconductance amplifier containing the current mirror with a low static current. The current mirror includes: a load with first end and a second end, the first end coupling to a first input current and a fixed voltage difference existing between the first and second ends; a first transistor, whose drain is coupled to the second end of the load, whose gate is coupled to the first end of the load, and whose source is coupled to a second input current; and a second transistor, whose drain is coupled to a third port and an output current, whose gate is coupled to the second end of the load, and whose source is coupled to the ground. The transconductance amplifier contains: a voltage amplifier stage, a transconductance stage, and a current amplifier stage for amplifying the current and containing the current mirror.

Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control means. It uses the resistor ladder that is structured with various fixed resistors to implement the shunt control means. The cut-off frequency of a filter is associated with the time constant, which is determined by equivalent resistance and equivalent capacitance value in the filter circuit; therefore, the filter of the present invention allowed users to fine tune the cut-off frequency linearly through the shunt control means when the variation of the environment or process parameters of manufacture cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. The present invention also provides a means for programming the cut-off frequency to a desirous frequency value dependent upon the conditions of application within a big range. Thus, it can be used in many purposes widely with the same filter circuit.

Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control devices. It uses the linear property of the MOSFET to implement the shunt control devices. Based on the first-ordered linear analysis of the transfer function of the active-RC filter, it is found that the cut-off frequency of the active-RC filter can be tuned via the effective small-signal current controlled by the shunt control devices. Therefore, the filter of the present invention allowed users for fine tune the cut-off frequency linearly through the shunt control devices when the variation of the environment or procedure parameters of manufacture (i.e. thermo-effects) cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. In addition, it needs the different cut-off frequency from the different application.

Abstract: A tuning loop which can tune the cut-off frequency of an active RC filter is disclosed. The cut-off frequency is determined by equivalent resistance and equivalent capacitance in an active RC filter, therefore, the tuning loop changes the equivalent resistance to tune the cut-off frequency. The time constant of the circuit is compared to see if it is equal to the applied preset time cycle after the equivalent resistance value is changed. The cut-off frequency of the filter is tuned to a preset value when the time constant in the circuit is equal to the applied preset time cycle, or the equivalent should be changed until the time constant equal to the applied preset time cycle. A precise result can be obtained after being tuned by tuning loop due to the each component of the tuning loop are operated in an environment which is equivalent to the active RC filter.

Abstract: A programmable/tunable active low-pass filter at least has the resistors, capacitors and shunt control means. It uses the resistor ladder that is structured with various fixed resistors to implement the shunt control means. The cut-off frequency of a filter is associated with the time constant, which is determined by equivalent resistance and equivalent capacitance value in the filter circuit; therefore, the filter of the present invention allowed users to fine tune the cut-off frequency linearly through the shunt control means when the variation of the environment or process parameters of manufacture cause the cut-off frequency drift, thus, the cut-off frequency can be kept in a constant value. The present invention also provides a means for programming the cut-off frequency to a desirous frequency value dependent upon the conditions of application within a big range. Thus, it can be used in many purposes widely with the same filter circuit.

Abstract: A frequency-tuning loop of the invention used in the Transconductor-Capacitor filter is composed of: a first switching device and a second switching device, both having two signal-inputting ends and two signal-outputting ends for switching the output of two signals alternately from two signal-outputting ends according to a fixed clock signal. A transconductor's inputting ends linking to the two signal-outputting ends of said first switching device. One end of a first switch linking to the positive outputting end of the transconductor and the other end linking to the first capacitor and a signal-inputting end of the second switching device. One end of a second switch linking to the negative outputting end of the transconductor and the other end linking to the second capacitor and another signal-inputting end of the second switching device; and a integrated circuit composed of an integrator, a third capacitor, and a fourth capacitor.

Abstract: A receiving method for dual-mode receiver. When a received communication signal is a wideband signal, the dual-mode receiver is configured as a direct-conversion receiver, and when a received communication signal is a narrowband signal, the dual-mode receiver is configured as a low-IF receiver.

Abstract: A frequency-tuning loop of the invention used in the Transconductor-Capacitor filter is composed of: a first switching device and a second switching device, both having two signal-inputting ends and two signal-outputting ends for switching the output of two signals alternately from two signal-outputting ends according to a fixed clock signal. A transconductor's inputting ends linking to the two signal-outputting ends of said first switching device. One end of a first switch linking to the positive outputting end of the transconductor and the other end linking to the first capacitor and a signal-inputting end of the second switching device. One end of a second switch linking to the negative outputting end of the transconductor and the other end linking to the second capacitor and another signal-inputting end of the second switching device; and a integrated circuit composed of an integrator, a third capacitor, and a fourth capacitor.